[Offload] Make olLaunchKernel test thread safe (#149497)

This sprinkles a few mutexes around the plugin interface so that the
olLaunchKernel CTS test now passes when ran on multiple threads.

Part of this also involved changing the interface for device synchronise
so that it can optionally not free the underlying queue (which
introduced a race condition in liboffload).

1 files changed, 4 insertions, 0 deletions

diff --git a/offload/include/Shared/APITypes.h b/offload/include/Shared/APITypes.h
index f376c7dc861f..8c150b6bfc2d 100644
--- a/offload/include/Shared/APITypes.h
+++ b/offload/include/Shared/APITypes.h
@@ -21,6 +21,7 @@
 
 #include <cstddef>
 #include <cstdint>
+#include <mutex>
 
 extern "C" {
 
@@ -76,6 +77,9 @@ struct __tgt_async_info {
   /// should be freed after finalization.
   llvm::SmallVector<void *, 2> AssociatedAllocations;
 
+  /// Mutex to guard access to AssociatedAllocations and the Queue.
+  std::mutex Mutex;
+
   /// The kernel launch environment used to issue a kernel. Stored here to
   /// ensure it is a valid location while the transfer to the device is
   /// happening.